1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and more particularly to, a method for manufacturing a flash memory device.
2. Discussion of Related Art
A process for forming a tunnel oxide film of a flash memory device forms a gate oxide film for high voltage on the whole surface of a semiconductor substrate, removes the gate oxide film for high voltage formed in a cell region and a low voltage region, and forms an appropriate thickness of tunnel oxide film in the cell region and the low voltage region.
However, the general process for removing the gate oxide film for high voltage formed in the cell region and the low voltage region does not completely remove the gate oxide film for the high voltage. The residual gate oxide film for high voltage deteriorates quality of the tunnel oxide film and uniformity of a thickness thereof.
There are thus increasing demands for a method for manufacturing a flash memory device which does not have detrimental effects on quality of the tunnel oxide film and uniformity of the thickness thereof.